Here's why:

* Acids have a pH lower than 7 and release hydrogen ions (H+) in solution.

* Bases have a pH higher than 7 and accept hydrogen ions (H+) in solution.

Antacids work by neutralizing the excess acid in your stomach, which is primarily hydrochloric acid (HCl). This is achieved by the antacid's ability to accept hydrogen ions (H+) from the acid, thereby raising the pH and reducing the acidity.

Common examples of antacids include:

* Calcium carbonate (Tums)

* Magnesium hydroxide (Milk of Magnesia)

* Sodium bicarbonate (Baking soda)

These compounds are all basic and react with acids to produce salts and water, effectively counteracting the stomach's acidity.